Is there a way to make a five sided bolt out of a 32 sided disk opening?
You must already have thought about this way but I'm not sure there's any other way around (by the way you could have used less than 32 vertices):

Create a 5 vertex circle (pentagone).
Subdivide it until it gets 30 vertices.
Select 1 of these vertices, ShiftCtrlB to bevel it. Do the same thing with another one. You now have a 32 vertex pentagone.
Bridge the cylinder with the pentagone.